Rocky Cummins; Cummins Prospect, Yentna Mining District, Matanuska-Susitna Borough, Alaska, USAi

Regional Level Types
Rocky Cummins; Cummins Prospect	Prospect
Yentna Mining District	Mining District
Matanuska-Susitna Borough	Borough
Alaska	State
USA	Country

This prospect lies within Denali National Park and Preserve.
Location: Clark and Hawley (1968) locate this prospect 4.5 miles southeast of Mt. Goldie at about 2900 feet elevation in the southwest quarter of Section 5, T. 30 N., R. 8 W., of the Seward Meridian within Denali National Park and Preserve. Also shown as locality 45 in Reed and others (1978) and locality 15 in Hawley and Clark (1973) in a southeasterly flowing tributary about three miles upstream on the west side of the Tokositna Glacier.
Geology: Mesozoic graywacke and argillite (KJs, Reed and Nelson, 1980) host steeply dipping, N75W striking, quartz veins in a 30 -foot-wide zone. Minor sporadic gold values occur within this zone, along with traces of silver, bismuth and tin (Cobb and Reed, 1980). Quartz is milky white, locally vuggy with minor pyrite, arsenopyrite, an unidentified gray-brown metallic mineral, white mica and free gold (Clark and Hawley, 1968; Hawley and Clark, 1973). The veins may be related to the Tertiary Kahiltna pluton (Tmk) mapped by Reed and Nelson (1980) to the northwest. Clark and Hawley (1968) report samples containing 0.02 to 1.4 ppm Au, up to 20 ppm Ag, with anomalous As, Bi, Sn and W. Stream sediment samples from four streams in the area between the Tokositna and Kahiltna Glaciers indicate the area is auriferous and could host other prospects (Clark and Hawley, 1968). See TL015.
Workings: Some small prospect pits and reconnaissance mapping, stream silt and rock sampling (Clark and Hawley, 1968) are all that have been done here. Clark and Hawley (1968) report samples containing 0.02 to 1.4 ppm Au, up to 20 ppm Ag, with anomalous As, Bi, Sn and W.
Age: Tertiary; mineralization is interpreted to be linked to the Kahiltna pluton (Tmk), part of the McKinley Sequence, that has been determined to range from 52.3 to 56.2 m.y. in age by K/Ar method (Reed and Lanphere, 1972; Reed and Nelson, 1980).

Commodities (Major) - Ag, Au; (Minor) - Bi, Sb, Sn, W
Development Status: No
Deposit Model: Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).

Other Databases

Link to USGS - Alaska:	TL016

Other Regions, Features and Areas containing this locality

References